Electronic structure and thermal conductance of the MASnI₃/Bi₂Te₃ interface: a first-principles study

To develop high-performance thermoelectric devices that can be created using printing technology, the interface of a composite material composed of MASnI₃ and Bi₂Te₃, which individually show excellent thermoelectric performance, was studied based on first-principles calculations. The structural stability, electronic state, and interfacial thermal conductance of the interface between Bi₂Te₃ and MASnI₃ were evaluated. Among the interface structure models, we found stable interface structures and revealed their specific electronic states. Around the Fermi energy, the interface structures with Te^II and Bi terminations exhibited interface levels attributed to the overlapping electron densities for Bi₂Te₃ and MASnI₃ at the interface. Calculation of the interfacial thermal conductance using the diffuse mismatch model suggested that construction of the interface between Bi₂Te₃ and MASnI₃ could reduce the thermal conductivity. The obtained value was similar to the experimental value for the inorganic/organic interface.